Probing spin–phonon coupling in magnetoelectric CaCu₃Ti₄O₁₂–NiFe₂O₄ composite nanostructures

Abstract

We investigated temperature‐dependent magnetic and phonon anomalies in epitaxial self‐assembled composite CaCu 3 Ti 4 O 12 –NiFe 2 O 4 films where NiFe 2 O 4 rods embedded in CaCu 3 Ti 4 O 12 matrix. The temperature evolution of the Raman spectra for pure NiFe 2 O 4 shows usual anharmonic behaviour in the temperature range of 80–300 K, while composite films show significant phonon anomalies in octahedral (O) site (Fe–O) phonon modes around 100 K, where sudden change in magnetic order is observed. The anomalies in A 1g (O site) phonon mode position and linewidth of NiFe 2 O 4 indicate lattice deformations around 100 K. It is suggested that spin strongly couples with phonons in magnetoelectric CaCu 3 Ti 4 O 12 –NiFe 2 O 4 nanostructures. Copyright © 2016 John Wiley & Sons, Ltd.